This page explains GKE on Bare Metal release 1.28 quotas and limits for Google Cloud projects, clusters, and nodes.
Limits
The following sections outline some basic limits for your clusters. Take these limits into account when designing your applications to run on GKE on Bare Metal.
Maximum user clusters per admin cluster
Admin clusters manage the lifecycle for user clusters and their associated nodes. Admin clusters control critical user cluster operations, such as cluster creation, cluster or node resets, cluster upgrades, and cluster updates. The total number of user cluster nodes is one of the primary factors limiting performance and reliability.
Based on ongoing testing, an admin cluster can reliably support a maximum of 100 user clusters having 10 nodes each for a total of 1,000 nodes.
Maximum number of pods per user cluster
We recommend that you limit the number of pods per user cluster to 15,000 or fewer. For example, if your cluster has 200 nodes, you should restrict the number of pods per node to 75 or fewer. Likewise, if you want to run 110 pods per node, you should restrict the number of nodes in your cluster to 136 or fewer. The following table provides examples of configurations that are and aren't recommended.
| Pods per node | Nodes per cluster | Pods per Cluster | Result |
|---|---|---|---|
| 110 | 200 | 22,000 | Too many pods, not recommended |
| 110 | 136 | 14,960 | Within limit |
| 100 | 150 | 15,000 | Within limit |
| 75 | 200 | 15,000 | Within limit |
The maximum number of pods per user cluster recommendation takes precedence over the recommendations for pods per node and nodes per user cluster in the following sections.
Maximum number of nodes per user cluster
We test GKE on Bare Metal to run workloads with up to 500 nodes. However, to ensure optimal performance and reliability, we recommend that you don't exceed 200 nodes per cluster when running workloads in production.
| Cluster type | Minimum nodes | Recommended maximum nodes | Absolute maximum nodes |
|---|---|---|---|
| User, Standalone, or Hybrid | 1 | 200 | 500 |
For single-node clusters, you must remove the
node-role.kubernetes.io/master:NoSchedule taint to run workloads on the node.
For details, see
Kubernetes taints and tolerations.
Maximum number of pods per node
GKE on Bare Metal supports the configuration of maximum pods per node in
the nodeConfig.PodDensity.MaxPodsPerNode setting of the cluster configuration
file. The
following table shows the minimum and maximum values supported for
MaxPodsPerNode, which includes pods running add-on services:
| Cluster type | Minimum allowed value | Recommended maximum value | Maximum allowed value |
|---|---|---|---|
| All HA clusters and non-HA user clusters | 32 | 110 | 250 |
| All other non-HA clusters | 64 | 110 | 250 |
Maximum number of endpoints
On Red Hat Enterprise Linux (RHEL), there's a cluster-level limitation of
100,000 endpoints. This number is the sum of all pods that are referenced by a
Kubernetes service. If two services reference the same set of pods, this
situation counts as two separate sets of endpoints. The underlying nftable
implementation on RHEL causes this limitation; it's not an intrinsic limitation
of GKE on Bare Metal.
Mitigation
For RHEL, there are no mitigations. For Ubuntu and Debian systems, we recommend
switching from the default nftables to legacy
iptables on
large-scale clusters.
GKE Dataplane V2
GDCV for Bare Metal uses GKE Dataplane V2, a cluster dataplane implemented with Cilium and eBPF, which is optimized for Kubernetes networking.
GKE Dataplane V2 NetworkPolicy limits
GKE Dataplane V2 uses Cilium to manage Kubernetes NetworkPolicy resources. The
following limits apply to your GKE on Bare Metal clusters:
| Dimension | Supported limits |
|---|---|
| Maximum change rate for namespace labels | At most, one change per hour for each namespace.
In most cases, this limit isn't necessary. As long as changes aren't frequent, such as every second, or the number of Cilium identities (unique label sets) isn't close to the limit: 16,000 label sets with allow all network policies, or 65,535 label sets per cluster. |
| Maximum number of Service endpoints per cluster | 100,000 endpoints is the tested and recommended limit. The hardcoded limit for Service endpoints is 262,000. |
| Maximum number of network policies and rules | At most, 40,000 network policies and 80,000 rules. For example, you can specify 40,000 network policies with two rules each, or you can specify 20,000 policies with four rules each. |
| Maximum change rate for network policies | At most, 20 changes (creations or deletions) per second. |
| Maximum number of unique pod label sets | 65,535 (216-1). This is the Cilium security identity limit. |
| Maximum number of unique pod label sets selected by policy selectors | 16,000 (the fixed eBPF map size). A given policy selector map entry consists of the following: security-identity, port, and protocol. |
GKE Dataplane V2 eBPF limit
The maximum number of entries in the BPF lbmap for Dataplane V2 is 65,536. Increases in the following areas can cause the total number of entries to grow:
- Number of services
- Number of ports per service
- Number of backends per service
We recommend that you monitor the actual number of entries used by your cluster to ensure that you don't exceed the limit. Use the following command to get the current entries:
kubectl get po -n kube-system -l k8s-app=cilium | cut -d " " -f1 | grep anetd | head -n1 | \
xargs -I % kubectl -n kube-system exec % -- cilium bpf lb list | wc -l
We also recommend that you use your own monitoring pipeline to collect metrics
from the anetd DaemonSet. Monitor for the following conditions to identify
when the number of entries are causing problems:
cilium_bpf_map_ops_total{map_name="lb4_services_v2",operation="update",outcome="fail" } > 0
cilium_bpf_map_ops_total{map_name="lb4_backends_v2",operation="update",outcome="fail" } > 0
LoadBalancer and NodePort Services port limit
The port limit for LoadBalancer and NodePort Services is 2,768. The default
port range is 30000-32767. If you exceed the limit, you can't create new
LoadBalancer or NodePort Services and you can't add new node ports for
existing services.
By default, Kubernetes allocates node ports to Services of type LoadBalancer.
These allocations can quickly exhaust available node ports from the 2,768
allotted to your cluster. To save node ports, disable load balancer node port
allocation by setting the allocateLoadBalancerNodePorts field to false in
the LoadBalancer Service spec.
This setting prevents Kubernetes from allocating node ports to LoadBalancer
Services. For more information, see
Disabling load balancer NodePort allocation
in the Kubernetes documentation.
Use the following command to check the number of ports allocated:
kubectl get svc -A | grep : | tr -s ' ' | cut -d ' ' -f6 | tr ',' '\n' | wc -l
Bundled load balancer node connection limits
The number of connections allowed for each node used for bundled load balancing (MetalLB) is 28,000. The default ephemeral port range for these connections is 32768-60999. If you exceed the connection limit, requests to the LoadBalancer Service might fail.
If you need to expose a load balancer service that is capable of handling a substantial number of connections (for Ingress, for example), we recommend that you consider an alternate load balancing method to avoid this limitation with MetalLB.
Cluster quotas
You can register a maximum of 15 clusters by default. To register more clusters in GKE Hub, you can submit a request to increase your quota in the Google Cloud console:
Scaling information
The information in this document is relevant for planning how to scale up your clusters. For more information, see Scale up GKE on Bare Metal clusters.
Didn't find what you were looking for? Click Send feedback and tell us what's missing.